Modular Forklift Li-Ion Battery Packs With Relay-Based Isolation
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Solution Overview
Problem
Class I forklifts are typically powered by heavy lead-acid batteries, which pose challenges in handling, safety, space requirements, and maintenance, while lithium-ion batteries have not been effectively implemented due to weight and thermal stability issues.
Innovation Solution
A modular lithium-ion battery system for forklifts, comprising interchangeable, self-contained battery modules that can be easily removed and recharged, compatible with both lithium-ion and lead-acid chargers, and equipped with safety features to prevent arcing and overcurrents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If lithium-ion batteries are used in forklifts, then energy density and run time are improved, but thermal stability and safety deteriorate
Solution Approach 1:
The battery system is divided into multiple modular battery packs, each containing multiple battery cells arranged in series. This segmentation allows individual packs to be replaced without replacing the entire battery system, reducing downtime and improving maintenance efficiency while maintaining the high energy density benefits of lithium-ion technology.
Solution Approach 2:
A battery management system serves as an intermediary between the battery cells and the forklift's electrical system. This intermediary monitors and controls the charging and discharging processes, managing thermal conditions and preventing overheating, thereby ensuring safety while utilizing the high energy density of lithium-ion batteries.
2Ease of operation
If modular battery modules are used, then ease of replacement and charging is improved, but device complexity increases
Solution Approach 1:
The battery system is segmented into standardized modular packs that can be independently removed and replaced. Each module contains complete battery cells with integrated management circuits, allowing simple swap operations without requiring complex disassembly or specialized tools, thus improving ease of replacement.
Solution Approach 2:
The modular battery packs are designed with universal interfaces and standardized dimensions that allow them to be used across different forklift models. This universality simplifies the replacement process and reduces the need for model-specific components, offsetting the added complexity through standardization.
3Weight of moving object
If lithium-ion batteries replace lead-acid batteries, then weight is reduced, but thermal runaway risk increases
Solution Approach 1:
By dividing the battery system into separate modular packs with physical barriers between them, the potential propagation of thermal runaway is limited to individual packs rather than affecting the entire battery system. This segmentation maintains the weight advantages of lithium-ion batteries while reducing overall thermal risk.
Solution Approach 2:
The battery management system implements preemptive thermal monitoring and control measures that detect early signs of overheating and take corrective action before thermal runaway can occur. This beforehand cushioning approach allows the system to utilize lightweight lithium-ion batteries while mitigating their inherent thermal risks.
Data Source
AI summary
Many embodiments involve rechargeable battery assemblies that are forklift-battery-sized but that comprise multiple built in battery modules. A housing typically contains battery modules installed within the assembly as the assembly is typically symmetrical in configuration. Each battery module has an integrated battery supervisor system (BSS). A Battery Operating System Supervisor (BOSS) module processor serves as a battery management system for all the battery modules. The BOSS module grants permissions to battery modules to enable them to connect and disconnect from busbars at the appropriate times to prevent electrical issues. As a result of various combined features, many embodiments are able to optimize cycle-to-cycle discharge potential of the overall assembly through the use and control of one or more solid state relays associated with each module and that are controlled to connect or isolate the cells of the module from the larger assembly, particularly to isolate the cells if the module is discharged to or below a minimum charge threshold for that particular module.